The present invention relates to connectors for use with endotracheal tubes and catheters.
Connectors are used for coupling the breathing circuit connection from the output of conventional anesthesiology machines to the open proximal end of the endotracheal tube. The conventional connector generally is molded of relatively hard plastic or polymer material and consists of a hollow cylindrical body having a cylindrical input section, a cylindrical output section or spout, and a central portion to facilitate holding the connector between the thumb and fingers. The cylindrical input section is of standard and uniform size to receive over its outer surface the standard breathing circuit connection or elbow connector which is attached to the output of the flexible hose from the anesthesiology machine. The outer surface of the cylindrical input section usually is tapered, or slightly conical, to insure an airtight seal between the outer surface and the inner cylindrical surface of the breathing circuit connection. The airtight seal is achieved by firmly pressing the two mating surfaces together.
The cylindrical output section, or spout, of the conventional connector is of widely varying sizes to accommodate the different sizes of endotracheal tubes in use. The spout is tapered and is inserted into the open proximal end of the endotracheal tube of the proper mating size to achieve a tight press fit, thereby assuring an airtight seal between the spout and the endotracheal tube.
Modern endotracheal tubes and catheters are manufactured of polyvinyl chloride, a tough, though flexible, transparent or semi-transparent rubber-like material. This material is well suited for this use since its surface texture and pliability are readily controllable during manufacture. The material, however, does possess two characteristics which have presented some problems in its use for endotracheal tubes. The first is that the material tends to age with the passage of time as well as when exposed to certain atmospheric conditions, resulting in a loss of flexibility and clarity in color. The second is that when the material is subjected to stress forces, as by bending or expanding, a temporary or semi-permanent set occurs within the material. Upon removal of the stress-producing forces, this set will gradually dissipate, and the material will return slowly to its original shape.
This latter characteristic produces a problem when an endotracheal tube of polyvinyl chloride is used with the tapered spout of the conventional hard plastic connector. While a secure and tight-fitting coupling is achieved between the outer conical surface of the spout and the inner cylindrical surface of the proximal end of the endotracheal tube when the spout is first inserted into the endotracheal tube, this tight fit begins to diminish almost immediately as the forces produced in expanding the diameter of the endotracheal tube cause the polyvinyl chloride to lose its resiliency and to take on a semi-permanent set. In those cases where an operation upon a patient may consume a period of many minutes, not to mention hours, it has been found that the fit between the spout and the proximal end of the endotracheal tube has become loose. It is not uncommon, under these circumstances, for the connector to become completely detached from the endotracheal tube, thereby causing an immediate loss of anesthesia.
The problem is not as acute where the conventional hard plastic connector is used with catheters which are intended for intubation into the mucous canals of the patient for the purpose of drainage of viscous fluids. In this type of operation, the physician may, after intubation of the catheter, desire to remove the connector from the proximal end of the catheter. The hard plastic connector, with its smooth tapered spout, is more easily removed from the proximal end of a polyvinyl chloride catheter after the proximal end has expanded in diameter and the set has begun to take effect.
Connectors have been fabricated from a variety of different materials, other than hard plastic, including materials having a relatively pliable and resilient characteristic similar to that of natural rubber. While tight-fitting seals have been achieved with these connectors, the removal of the connector from the catheter or endotracheal tube is virtually impossible. The forces needed to be applied by the physician to remove the connector from the endotracheal tube or catheter are found to be too great. Such forces cause actual physical movement of the intubated endotracheal tube or catheter and its resulting trauma to the patient. This problem becomes extremely acute in those cases requiring the physical removal of the connector from an intubated endotracheal tube or catheter during operations performed in emergency situations.
One type of connector, known as the "Racine" connector, consists of a long, corrugated, silicone rubber tube having a cylindrical metal input section for coupling to the breathing circuit connection. The output section consists of a stretched silicone rubber diaphragm supported perpendicularly across the output end of the corrugated tube by a metal ring. A small circular hole is located in the center of the diaphragm.
The stretched diaphragm, with its center hole, is adapted for stretching over the outside surface of the proximal end of the endotracheal tube by expanding the diameter of the central hole. A relatively tight seal is achieved over the outside surface of the endotracheal tube rather than within its cylindrical inside surface. The "Racine" connector is usable with a number of sizes of endotracheal tubes without altering the diameter of the center hole in the stretchable diaphragm. While this type connector possesses some advantages over the conventional hard plastic connector, its cost is relatively high.
A number of additional serious problems exist with the use of the conventional connector. These problems, however, have been substantially eliminated by the introduction of the improved connector of the invention.
Accordingly, a principal object of the present invention is to provide an improved connector of a new type capable of providing a superior seal between connector and endotracheal tube.
Another important object is to provide a connector that may be installed easily upon an endotracheal tube or catheter and thereafter may be removed from the endotracheal tube without disturbance of the position of the endotracheal tube or catheter.
A further object is to provide a connector for coupling to the endotracheal tube which does not restrict or reduce the size of the lumen of the endotracheal tube.
An additional object is to provide a new type of connector for use with endotracheal tubes or catheters, which is rotatable with respect to the endotracheal tube or catheter without loss of the airtight seal and without disturbance of the position of the endotracheal tube.
Still another object of the invention is to provide a connector whose bore is appreciably larger than the lumen of the endotracheal tube for which it is designed to be used, thereby enabling larger suction catheters to be inserted into and through the connector and endotracheal tube in those operations in which a suction catheter may be required.
Further objects include providing an improved connector capable of producing a longer-lasting airtight seal with the conventional endotracheal tube, a superior coupling between connector and breathing circuit connection, and an improved means for securing the connector to the breathing circuit of the anesthesiology machine.